Let us begin with an example (diagram below). Suppose two people, Rose and Colin, play the following game: Rose has two cards labeled 1 and 4, respectively; Colin has cards labeled 1, 2, and 3. Each player knows the holdings of the other. Rose secretly selects one of her two cards, Colin one of his three. Then the two players simultaneously display their choices. If the sum of the two selected
... [Show full abstract] cards is even, Rose wins that many dollars from Colin; if the sum is odd, Colin wins that amount from Rose. The following diagram summarizes these rules from Rose’s point of view.